At LM76,
we are not trying to sell you anything but economical,
engineered solutions. We want your business
and we know that if we do a great job, you will call us
again. When selecting a linear bearing system for your
application,
there are a few things to keep in mind. I have outlined some
of these considerations below. Please call us with any
questions - we love your calls! Mike
Quinn VP Sales & Marketing - LM76

Whisper Slide

If you do not comply with the
2:1 Ratio, you will
notice binding, sticking and ratcheting. If your
pillow block spacing is less than 1, then you
must increase the distance between the
pillow blocks.

Whisper Slides are
an economical selection and possess some
meaningful - all around - advantages:

Sleeve bearing systems, like our Whisper Linear Slide, have
an inherent drawback called "stiction."
Because sleeve-bearings have a lot of contact area ( as
opposed to a point loaded ball or roller ),
they require a greater amount of force - than a ball or
roller - to get under way. We use a .3 multiplier
when we size these slides. EXAMPLE: If you had a 100
pound load applied uniformly over the
4 bearings of the carriage block, in a horizontal
orientation, it would take 30 pounds of force to get
the slide moving. Once the slide transitions from static to
dynamic, the frictional characteristics
become uniform and the force required drops dramatically.

Edge Loading: Edge Loading can be an issue with
sleeve-type linear bearings and systems.
If there is a moment load applied to these slides we have to
employ what is commonly called the
2:1 ratio between the length of the moment arm and the
distance between shafts ( horizontal orientation )and
distance between bearings on one shaft ( vertical
orientation ).

EXAMPLE VERTICAL: If I have a vertical lift system
and I have a 90° moment arm of 10" carrying
aload of 40 pounds then the distance between the bearings on
shaft must be a minimum of
5" apart inside to inside. Because Whisper Linear Slides
feature a carriage plate that employs
an aluminum extrusion top plate, we can make a longer plate
to accommodate the required
bearings spread. To be honest, I would like to see a 1:1
ratio on these vertical applications.

For low friction,
high loads and extreme moment loading, profile rail guides
are the
best answer. These bearings are capable of taking up to
65,000 pounds of load
per bearing ( Size 65 ) while ensuring high stiffness, high
accuracy and
extremely low friction.